From left to right in July: Ruben Barrales, president of the San Diego Regional Chamber of Commerce; San Diego Mayor Jerry Sanders; Tijuana Mayor Carlos Bustamante; and Alan Bersin, commissioner of Customs and Border Protection. / Courtesy photo

After nearly two years at the helm of U.S. Customs and Border Protection, Alan Bersin announced Thursday that he will step down on Dec. 30. A former U.S. attorney in San Diego, he oversaw the agency at a time of unprecedented resources for securing the southwest border.

Bersin’s supporters credit him for increasing enforcement, for his vision of boosting binational commerce and for maintaining strong relations with Mexico. Detractors say he has failed on multiple fronts before and during his time as commissioner, including his lack of collaboration with community groups, his role in “militarizing” the border and his advocacy of policies that pushed more migrants into harsh terrain — leading to more deaths.

In the statement announcing his resignation, Bersin, 65, did not specify his reason for leaving. But he had never received congressional confirmation, so President Barack Obama had to make a recess appointment for him. Bersin’s term was set to end Dec. 31.

Public-sector positions held by Alan Bersin

•1993-1998: U.S. attorney for Southern District of California, including as “border czar” for much of that time.

•1998-2005: Superintendent of San Diego Unified School District.

•2005-2006: California secretary of education.

•2006-2009: Chairman of San Diego County Regional Airport Authority.

•2009-2010: Assistant homeland security secretary for international affairs. He’s again called “border czar.”

•2010-present: Commissioner of U.S. Customs and Border Protection.

As commissioner, Bersin oversees more than 57,000 employees and a budget of $11.2 billion in fiscal year 2011. The agency is charged with securing the United States’ borders, including its ports of entry, with customs inspectors and Border Patrol agents.

Under Bersin, the Border Patrol got more agents — to its current total of 20,000 plus — more fences were erected and more high-tech surveillance gadgets were added. The National Guard also joined the ground force along the country’s southwest boundary.

Bersin’s knowledge of the border region, plus his Spanish speaking skills, gave him credibility. But it was how he used that experience that elicited praise and criticism.

“No one understands the border and how it works better than Alan Bersin,” said Ruben Barrales, president and CEO of the San Diego Regional Chamber of Commerce. “He understands the manpower that it takes, the technology you need and the infrastructure you need to move legitimate goods and people across the border.”

Bersin’s good working relationship with Mexican officials was an asset during crisis points, including the killing of a U.S. Immigration and Customs Enforcement agent Jaime Zapata this year in San Luis Potosi, said David Shirk, director of the Trans-Border Institute at the University of San Diego.

His main role “was to build a strong case to show that Obama was doing everything possible to address the border-security concerns that many Americans have, so that we can finally have a discussion on other” issues including immigration reform, Shirk added.

In the past year, apprehensions have fallen and drug seizures have risen. Bersin has credited the U.S. government’s solid flow of funding and new technology for bringing about those trends. But Shirk and other analysts said the drop in illegal immigration from Mexico has been driven by fewer economic opportunities in the United States. They question the effectiveness of strategies such as building border fences and other means of boosting enforcement.

Civil-rights and immigrant advocates said Bersin falsely promoted the border region as lawless and fed fears that resulted in an unwarranted enforcement response, a record number of migrant deaths and a higher level of tension between his agency and community members.

They describe him as a hard-charging lawman with little regard for grassroots organizations.

“His border walls and massive amounts of enforcement are the norms for the border,” said Christian Ramirez of the American Friends Service Committee in San Diego. “It was because of his design and his policies that we have a mounting death toll on this border.”

Given Bersin’s history, immigration advocates’ hopes for his term as commissioner were minimal, said Kevin Keenan, executive director of the American Civil Liberties Union in San Diego.

“And yet Bersin managed to disappoint,” Keenan said.

Bersin deserves credit for an inspiring vision of the border that recognized “the more robust the regulated exchange with Mexico of labor and capital, the more controlled and humane the border becomes,” Keenan said. But the Obama administration did not deliver and Bersin did little on his own, he said.

Born in Brooklyn, Bersin has made San Diego his home since the 1990s. His public positions include superintendent of San Diego schools and chairman of the San Diego County Regional Airport Authority.

But border issues propelled him to the national stage. As a U.S. attorney under former President Bill Clinton, Bersin was known as the “border czar” who helped craft Operation Gatekeeper in 1994. The program tightened security in the San Diego sector of the border and in turn pushed migrants into more hostile environments such as mountains and deserts.

Border experts said the program launched the momentum for today’s record-high number of agents and inspectors.

He “was a pretty straight shooter, he didn’t play games with us during our interactions with him,” Moran said. He was “definitely someone who was concerned about the welfare and opinion of the frontline agents.”